How Social Networks Impact Drinking Habits

Adding to their previous research examining the impact of social contagion on everything from smoking to generosity, Harvard sociologist Dr. Nicholas A. Christakis and University of California, San Diego, political scientist James Fowler most recently teamed up to examine how social networks influence alcohol consumption.

This time around Christakis, Fowler and colleagues analyzed data gathered from more than 5,000 participants in the Framingham Heart Study (FHS), an ongoing, longitudinal study that started in 1948 and has followed multiple generations, tracking health information — including self-reported alcohol consumption habits — every two to four years.

The researchers then created a second data set based on study participants’ social networks. (Of seven different groups included in the FHS study, researchers focused on the cohort that entered the study in 1971, yet also used data from members of other cohorts linked to this primary group.)

After a statistical analysis of social connections and alcohol consumption patterns, the researchers found that, like so many other things, drinking habits can be contagious: if a close connection (friend, relative, coworker) drank heavily — defined as an average of one drink per day for women and two drinks per day for men — participants were 50% more likely to drink heavily themselves; if someone connected by two degrees of separation (a friend of a friend) drank heavily, participants were 36% more likely to do so.

The social impact of drinking continued to three degrees of separation — that is, if your friend’s mom’s cousin drinks heavily, you’re about 15% more likely to do so too — but disappeared after four degrees of separation, the study authors found.

In the study, published in the Annals of Internal Medicine, the researchers found no correlation between relationships with heavy drinkers and influence on moderate drinking habits. Yet they did find that, after controlling for other factors including age, sex and education, social connection to multiple heavy drinkers had a significant impact on a person’s own drinking habits — for every additional heavy drinker in a person’s social network, an individual’s likelihood of heavy drinking increased by 18%, and likelihood of abstaining from alcohol decreased by 7%.

Yet, the researchers observed the opposite effect as well — for every social contact who abstained from alcohol, a person’s likelihood of heavy drinking decreased by 10%. What’s more, for every teetotaling friend, aunt or cousin, people were 11% less likely to be moderate drinkers, and 22% more likely to abstain from drinking as well.

The findings, the authors write, suggest “that social network effects may have both positive and negative health consequences for alcohol consumption behavior, depending on the circumstances.”

Additionally, they conclude, the results of this study add to previous findings supporting the notion that “because persons are connected, their health is also connected.” Gaining a better understanding of how social networks impact individual habits and behaviors could offer insight into more effective public health initiatives, the authors argue, concluding that the study findings “reinforce the idea that drinking is a public health and clinical problem that involves groups of interconnected people who evince shared behaviors, and targeting those behaviors would rightly involve addressing groups and not just individuals.”

Corrected: The original post mistakenly stated that James Fowler is a political scientist at the University of California, Davis. He is an associate professor in the Center for Wireless and Population Health Systems at Calit2 and in the political science department at the University of California, San Diego.